Control system



Aug. 31 1926.

I I H. L. BLOOD CONTROL SYSTEM Filed August 9, 1923 2 Sheets-Sheet 1WVENTQR. N 7635173150166 ATTORNEY.

Aug. 31 1926.

1,598,115 H. L. BLOOD CONTROL SYSTEM FiledAugust 9, 1923 2 Sheets-Sheet2 INVENTOR.

TTORNEY.

Patented Aug. 31, 1926.

HAROLD L. BLOOD,

UNITED STATES-PATENT OFFICE.

OF NORTH PLAINFIELD, NEW JERSEY, ASSIGNOR TO NILES-BE- KENT-PONDCOMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

cou'rnor. svsrnm.

a control system for a planer or a similar machine tool that shall beprovided with auxiliary means for extending the limit of the motorfeeding movements beyond the limit now possible when the usual limitswitch is used in a control system.

Another object of my invention is to provide a planer control system ofthe above indicated character having a limit switch for limiting thelength of the feeding movements effected by the feed motor that shall beprovided with auxiliary means associated with the limit switch forextending the feeding movements of the motor beyond the limit possibleto be effected by a limit switch.

A further object of my invention is to provide a control system of theabove indicated character that shall be provided with a limit switch foreffecting feeding movements of the feed motor and that shall be providedwith auxiliar electrical means associated with the limit switch forextending the feeding movements of the feed motor to difierent multiplesof the usual feeding movement.

In control systems for operating planers and others machine tools havinga reciprocating member, it is usual to provide a main motor which isoperated by a pilot switch in accordance with the movement of thereciprocating member. In many control systems the pilot switch not onlycontrols the main motor for operating the reciprocating member, but alsocontrols a feed motor for feeding and traversing the cutting toolscarried by the machine. A limit switch, which is usually of the drumtype, is mechanically connected to the feed motor and during the feedingoperation limits the feed motor to a predetermined number of rotations.Thus, the pilot switch starts the operation of the feed motor and thelimit switch limits or stops the feeding movement. In many cases it isdesirable to effect a greater feeding movement than is possible with theusual 1 type of limit switch. Thus, in certain fin ish ng operations itis desirable to obtain a feed at least twice as large as can be effectedwith the usual type of limit switch. However, during roughing operationsa v ry small feeding movement is desirable.

if, Application filed'August 9,1923. Serial No. 656,493.

;-In a control system constructed in accordance with my invention,auxiliary electrical means is associated with the usual limit switch inorder to effect feeding movements which are different multiples of thefeeding movement now possible to be effected by the usual limit switch.Selective means is provided whereby the control system may be operatedby the limit switch in the usual manner and efiect normal feedingmovements or may effect feeding movements which are different multiplesof the normal feeding movements. The means disclosed for extending thelimit of the feeding movements effected by the feed motor may beutilized in a system having a feed motor which operates in a continuousdirection or in a control system having a feed motor which reverses inaccordance with the movement of the planer table. Thus my invention isapplicable to the control system dis closed in the patent to Keefer, etah, 1,299,192 dated April 1, 1919, and to the control system disclosedin the patent to Greenleaf, et al., No. 1,321,203 dated November 11,1919.

In the accompanying drawings Figure 1 is a diagrammatic view of a planercontrol system embodying my invention.

Fig. 2 is a front elevational view of a planer adapted to be operated inaccordance with my invention.

Fig. 3 is a diagrammatic view of a modification of my invention.

Referring to Fig. 2 of the drawings, a planer 1. is shown whichcomprises a, base 2 and uprights 3. A table 4., which carries the work,is reciprocated on the base 2 by means of a main motor 5. which carriesthe cutting toolsT, is adjustably mounted on the uprights 3. The cutting tools 7 are fed along the rail 6 by means of a feed motor 8 in anysuitable manner. In Fig. 2 of the drawings, the motor 8 is shown mountedon the arch which connects the two uprights 3. A vertical shaft 9, whichis located outside one of the uprights 8, is connected to the shaft ofthe motorby any suitable gearing. The shaft 9, in the usual manner, isconnected by bevel gear wheels to a gear wheel 10 whichcontrols thefeeding and traversing movement of the cutting tools. The gear wheel 10is connected to a feed gear wheel 11. by means of a con A cross rail 6,

necting rod 12 and an adjustable pin 13. The pin 13 and the connectingrod 12 may be adjustable to elfeet limited changes in the feedingmovement ell'ected by the cutting tool. Inasmuch as the feedingconnections to the cutting tool are fully described in the patent toGreenleaf, et al. and in the patent to Keefer. et al., referred toabove, a further description thereof is deemed unnecessary.

In the above feeding mechanism, it will be noted the gear wheel 10 maybe rotated in a continuous direction or may he oscillated through 180degrees in order to effect feeding movements of the gear wheel 11. Thusthe motor 8 may be rotated in one direction until the gear wheel 10 ismoved through 180 degrees and may be reversed to return the gear wheel10 to initial position or may continue its initial movement until thegear wheel 10 is back to initial position. The shaft 9 carries a limitswitch 15 which will be described in detail when reference is made toFig. 1 of the drawings.

The planer table at carries two dogs 16 and 17 which are adaptedrespectively to engage levers 18 and 19. The levers 1S and 19 areconnected by links 20 and 21 to a pilot switch 22. The pilot switch 22controls the main motor 5 and also the feed motor 8 in accordance withthe movement of the plaiier table 1. At the end of the forward orcutting stroke of the planer table, the dog 16 engages the lever 18 tooperate the pilot switch so as to reverse the direc tion of rotation ofthe main motor 5. At the end of the return stroke of the planer table-lt;. the dog 17 engages the lever 19 to operate the pilot switch 22 soas again to reverse the direction of rotation of the main motor 5.

Referring to Fig. 1 of the drawings, a control system illustrated forcontrolling the planer 1 shown in Fig. 2 of the drawings. The main motor5 is controlled by two main switch 21 and 25 and an accelerating switchii. The feed motor 8 is shown controlled by a feed switch 27.

The main motor 5 comprises an arn'iature a shunt field magnet winding29, a series field magnet winding and an interpole winding 31. The shuntfield magnet winding 29 is connected in circuit with two resisters 32and 33 which are controlled in a manner to be hereinafter set forth forgoverning the speed of the main motor. An armature resistor 3-1. whichis controlled by the accelerating switch 26. is provided for governingthe acceleration of the main motor 5.

The feed motor 8 comprises an armature a series field magnet winding 36.and a mt field magnet winding 37. A resistor ob is provided in thearmature circuitof the feed motor 37 for dynamically braking the feedmotor upon release of the feed switch 27.

The main switch 24: comprises a switch arm 39 which carries two contactmembers fl-O and 11. The contact member 10 is adapted to engage astationary contact member '12 when the switch in an operative positionand the contact member -11 is adapted to engage a stationary contactmember -13 when the switch is in :1 released position. A main magnet 14:is provided for operating the switch arm 31) and a holding magnet -15 isprovided for preventing operation of the switch arm 39 when the mainswitch 25 is in an operative position and also for preventing operationof the switch arm 19 when a dynamic braking current is lowing throughthe main motor.

The main switch 25 comprises a pivotally mounted switch arm 16 whichcarries two contact members 1-? and -18. The contact member -17 adaptedto engage a stationa r contact member 49 when the switch is in anoperative position and the contact member 18 is adapted to engage astationary contact member 50 when the switch in a released position. Amain magnet 51 provided for operating the switch arm lo and a holdingmagnet 52 provided for prevent ing operation of the switch arm to whenthe main switch 21 is in an operative position and for preventingoperation of the switch arm when a dynamic braking current is flowingthrough the main motor.

A pin 53 which extends from the side of the switch arm 1b is adapted toopen a switch 51 when the main switch 23 is oper ated. Normally theswitch serves to exclude the resistor 32 and a portion of the resistor33 from the circuit of the shunt field magnet winding 29. However. uponoperation of the main switch 25 to elfect a return stroke of the planertable -l. the switch 51 is opened to insert. all the lOFlrlOl S and theresistor 32 in the circuit of the shunt field magnet winding. Thus thespeed of the motor during the return stroke of the main motor isincreased. preventative resistor is included in the circuit of the shuntlicld magnet winding 29.

The accelerating switch 26 com irises a pivotally mounted switch arm at;which carries two contact members 57 and F8. The contact member which isinsulated from the switch arm 50, is adapted to engage a stationarycontact member 5!) when the switch arm is in :1 released position. Thecontact member 57 is adapted to emrage a stationary contact member (it)when the ac celerating switch in an operative position to short circuitthe resistor Ill. (31 is provided for operating arm 56.

The feed switch 27 comprises a pivotally mounted switch arm (32 whichcarries two magn t the switch motor 8.

contact members 63 and 64. The contact member 64 is adapted to engage astationary contact member 65 when the switch arm is in the releasedposition and the contact member 63 is adapted to engage a stationmycontact member 66 when the switch arm is in an operative position. A maet coil 67 is provided for operating the switch arm 62. A blow-out 001168 is associated with the contact members of the feed switch 27 andblow-out coils 69 are provided for the contact members of the mainswitches 24 and 25 and the accelerating switch 26.

A switch 70 is provided for connecting the control circuits to a supplycircuit comprising conductors 71 and 72 and also for completing certainof the control circuits. The switch 70 comprises three switch blades 73,74 and 75 which are adapted to engage contact members 76, 77, 78, 79 and80. I The pilot switch 22 comprises contact segments 81 to 85 inclusive,which are adapted to engage contact members 86 to 93 inclusive.

The limit switch 15, which is mounted on the shaft 9, comprises twocontact segments 94' and 95, and a contact segment 97. The contactsegments 94 and 95 extend half way around a, drum 96 and the segment 97encircles the drum 96. The contact segments 94, 97 and 95 respectivelyengage contact members 98, 99 and 100. Adjacent to the limit switch 15is mounted an auxiliary switch 101 which serves to extend the feedingmovements of the feed The auxiliary switch 101 comprises a drum 102which is mounted on a suitable shaft 103. The shaft 103 is connectcd tothe shaft 9 by means of gear wheels 104 and 105. Preferably, the gearwheels 104 and 105 are of such size that the shaft 9 effects tworotations for each rotation of the shaft 103. It is to be understood,however, that my invention is not limited to any such ratio, inasmuch asmy invention is equally applicable to other planers than the planerillustrated in the drawings. Three contact segments 106, 107 and 108,which are mounted on the drum 102, are respectively adapted to engagecontact members 109, 110 and 111.

A. two pole double throw switch 112 is provided for connecting the pilotswitch 22 to the limit switch 15 and the auxiliary switch 101. Theswitch 112 comprises two switch blades 113 and 114 which are adapted toengage contact members 115 to 120, inclusive. A reversing switch 121,which is connected in the circuit between the pilot switch 22 and thelimit switch 15 and the auxiliary switch 101, is provided for effectingfeeding operation at either end of the stroke of the planer table.

Assuming the switch blades 114 and 113 of the switch 112 to respectivelybridge the contact members 118. and and 117 and 119, the feed switch 27will be controlled by the limit switch 15 and the pilot switch 22 foreffecting normal feeding movements by the feed motor 8. At the end ofthe cutting stroke,

18, as shown in Fig. 2 of the drawings, to operate the pilot switch 22.The contact segment 85 is moved to bridge the contact fingers 92 and 93and the contact segments '81 and 82 are moved to bridge the contactfingers 86; and 87. The bridging of the contact fingers 92 and 93completes a circuitthrough the magnet 51 of the main switch The circuitthrough such magnet extends i'rom the supply conductor 71 through themagnet 51, contact fingers 92 and 93, which are bridged by the contactsegment 85, switch arm 39, contact members 41 and 43, holding coil 45,series field magnet winding 30, and the switch blade 74 to the supplyconductor 72.

The main switch 25 is operated to complete a circuit through the mainmotor 5. The circuit through the motor 5 ext-ends from the supplyconductor 71 through the contact members 49 and 47, switch arm 46,switch blade 73, armature 28, interpole winding 31, acceleratingresistor 34, switch arm 39, contact members 41 and 43, holding coil 45,series field winding 30, and the switch blade 74 to the supply conductor72. The main motor 5 is operated in a direction to effect a returnmovement of the table 4. The contact segments 81 and 82, which bridgethe contact fingers 86 and 87, serve to complete a circuit for operatingthe accelerating switch 26. The circuit for op erating the acceleratingswitch extends from the supply conductor 71 through the contact members49 and 47, switch arm 46, switch blade 7 3, contact fingers 87 and 86,which are bridged by the contact segments 81 and 82, magnet 61, seriesfield magnet, winding 30, and the switch blade 74 to the supplyconductor 72. Theacceleratingswitch 26 is operated to short circuit theresistor 34.

Prior to the operation of theaccelerating switch, a circuit of the shuntfield magnet winding 29 extends from the supply conductor 71 throughcontact members 59 and 58, winding 29, and the switch blade 74 to thesupply conductor 72. Upon operation of the accelerating switch, thecircuit of the shunt field magnet winding extends through the resistor33 and the resistor 32. Thus the speed of the main motor is increasedduring the return movement of the planer table. As heretofore set forth,the switch arm 46 opens the switch 54 to insert all the resistor 33 andthe resistor 32 in the circuit of the shunt field magnet winding.

The contact segment 84 on the pilot switch bridges the contact fingers90 and 91 to etfeet a feeding movement by the motor 8. circuit iscompleted by the contactsegment the dog16 engages the lever t'ect afeeding 5: 1 which extends from the supply conductor 71 through magnetcoil 67, contact fingers 99 and 98. which are bridged by the contactsegments 91 and 97. contact members 117 and 119,. contact tingers 91 and90, which are bridged by the contact segment 81, and the contact lingersTS and T7,.ivhich are bridged by the switch blade H. to the supplyconductor T2. The feed magnet 27 is operated and a circuit C(NTlPltlCtlfor operating the feed motor. The circuit through the teed motor extends11'0111 the supply conductor 71 through contact member T0, switch blade75. armature 13. resistor 38, contact members (i3 and (36. and theseries lield n'iaguet winding Sb to the supply conductor T2. The feedmotor 8 operates the gear wheel 10. shown in Fig. 2, through 180 degreesto elmovement 01 the cutting tool. Upon movement ofthe gear wheel 10through 180 degrees. the contact: segn'icnt 01 on the limit switchdisengages the contactmember 95 to open the 'leed switch. The circuit Vof the feed motor is thus opened.

lit the end of the return stroke of the plane the dog 17 engages thelever 19 to reverse the position of the pilot switch. In the reverseposition of the pilot switch. the contact segment 83 bridges the contactlingers ST and S8 to complete a circuit tor operating the main switchit. The contact segments and S2 bridge the contact segments 93 and S0for operating the accelerating switch 26 and the contact member 81bridges the contact members 89 and 90 for eli ecting move ment of thefeed motor 8.

Upon release of the switch a dynamic braking circuit is completedthrough the main motor 7) which includes the two holding coils 15 andand the resistor The we holding coils :32 and prevent the operation ofeither main switch until the dy namic breaking curieut ceases to flow.Upon release of the feed switch 27, a dynamic braking circuit completedthrough the armature 35 and the resistor 38 by the engagcmentbetween thecontact members (31; and 65.

The circuit completed by the contact segment bridging the contactfingers ST and SS extends from the supply conductor 71 through themagnet -14. contact lingers ST and SS which are bridged by the contactsegnient- S3. switch blade 73. switch arm -10. contact members 18 and50, holding coil series l'ield iii-agnet winding 3-30 and the switchblade 7:1- to the supply conductor 72. The main switch 21 is operatedand a circuit is completed for operating the main motor to etiect acutting stroke by the planer table.

The circuit through the motor extends from the supply conductor 71through the contact members: -12 and 1-0. switch arm 30, resistor 31.interpole winding 31, armature 2S, switch blade 73, switch arm 16,contact members =18 and 50. holding coil 52. series field magnet winding10 and the switch blade 71- to the supplv conductor The acceleratingswitch 26 is then operated by a circuit which is completed by thecont-act segments S1 and on the pilot switch. Upon operation of theaccelerating switch, the circuit of the shunt field magnet winding 29 iscompleted through only a portion of the resistor 33 inasmuch as theswitch 5e1- is maintained in closed position. .iccordiiigly. the cuttingstroke ot the planer table. is etl'cct'ed at a reduced speed.

The circuit completed by the contact segment 81 extends from the supplyconductor T1 through the magnet (3T. contact lingers and 100 which arebridged by the contact segments 07 and 95. contact members 113 and 120,which are bridged by the switch blade 111, contact members 89 and 90.which are bridged by the contact segment 811" and c ntactmem ers TT andTS, which are bridged by the switch blade T1 to the supply conductor T2.The circuit of the feed motor S is then closed through the contactmembers i and (it; ot the ed switch 2?. Further movement 0! 180 degreesis eli'ected of the gear wheel 10. as shown in Fig. 2 oil the drawings.The movement of the gear wheel 10 serves to return the connecting rod 12to initial position. The .t'eed motor is stopped by the contact segmentdisengaging the. contact linger 100.

It it is desired to etl'cct double feeding u'iovcment by the motor. theswitch 112 is oi icrated so that th switch blade 111 bridges the contactmembers 116 and 11S and the switch blade 11-?) bridges the contactmembers 115 and 11?. The circuit for operating the feed switch 27 at theend of the cutting stroke extends from the supply conductor 71 throughthe magnet (37. contact fingers 110 and 109, which are bridged by thecontact segments 10(3 and 107, contact: members 115 and 117. contactlingers 00 and 91, which are bridged by the contact segment 81. and thecontact members TT and 78. which are bridged by the switch blade T1 tothe supply The feed switch 27 is operatconductor 42. ed for con'ipletinga circuit through the feed motor 8.

The circuit completed through the feed motor 8 is maintained closeduntil the contact segment separated from the contact finger However. thecontact segment 106 is not separated from the contact finger 109 untilthe motor has rotated the gear wheel 10 through 51-0 degrees. .Eyrotating such gear wheel through 5-10 degrees. it is apparent a doublefeeding movement is etlected. The first 1S0 d flttS movement of the gearwheel 10 effects a feeding movement of the cutting tool and the next 180degrees movement 01 the gear wheel 10 returns the feeding mechanism toinitial position. The

.- maintained closed unt 89 and 90 toeflect a movement of themotorormov1ngt wheel 10 effects a second eedingfmovement.

of the tceding mechanism and the cutting tool. ln order to effect suchmovement, the

ear;,wheels lU landa 105,. as heretofore set orth arc of such size as torotate the shaft 103 at half the speed of the shaft 9.. vMoreoveigthecontact segment 106 is arranged to extend threequarter s of the,wayaround the drum, 102 whereasthe contact segment 108 ;is.arrwged toextend only one-quarter the way around the drum 102. Thus, thecircuitabove traced through themagnet 67 for the feed switch 27 ismaintainedclosed while the shaft 108 efiects three quarters of a rotation. Therotating of the shaft 103 three-quarters of a rotation effects one andone-half rota.- tions of the shaft 9 and one and one-half frotations ofthe shaft '9 effects movement of the gear ,wheels 10 through 540degrees. .lTlms a double feeding movement of the motor is efi'ected. y

At the end of thereturn stroke, '3; econract segment 84 bridges thecontact,

H e gearjwheel 10 through 1%).degrees. Such I w 10 returns the feedingrnechanism to t ltra it eah s n c seg ply, conductor 7 1 throughcpntactfingers 110 an 111, which are bridged. by the. witch blade 114,confinge fi e 9 which are bridged y. the, a me t-e 7 tact members 77 and7 8,whlch are bridged by the. switch blade flgfto the supply con dlator; 2. The switch- 27. is operatedand a crew s qa ela eil-zthrqas 18... The: circuit throuzn i "the contact segment rated from thecontactfi Inasmuc as the segment 108 exten s only one-quarter. of the wayaroundthe drum 102, it is apparent the shafttl will efi'ect only one-half arevolution and, accordingly the gear wheel 10 will rotate through only180 de y es. I I 2 abo yst 108.iss e iter effecting double movement fthe feed motor, it is parent that it is immaterial whether the am 4s e es d-s ch sad i planer table movemen, operated in a or 1S1 cont nuousdirection as above described. In order to simplify the above system nomeans is illustrated forefiectin a traversing operation and no circuithr erand similar apparatus is illustrated. gflo ever it is to beunderstood that my invent oi i is equally applicable to systemsprovided. with means for effecting traversing operation in either d1-tentsabove mentioned.

rection as in the, g I

) g. 3 of the drawings, a

Referring to modification of my invention is illustrated.

for effecting double feeding movements of ,eed;

movement of the gear The. circuit completed by 84 extends from the supthe gm 16 and cone the feed motor is er'llL the motor. In themodification shown in Fig. 3, however, it is essential that the feedgear wheel126 is mounted ona shaft 127. The gear-wheels and 126 are of,such size as to effect 0 eration of the shaft 127 at one half the specofthe shaft 9. Thefshaft 127 also carries a cam member 128 which oper-'ates a. plunger 129 to control a switch 130. The 'plunger129 is forcedinto engagement withv the cam'member by means of a sprin member .131. gThe automatically operated switch 1301s connected in circuit with amanually operated switch 132 across the contact fingers 98 and 99 of thelimit switch 15. The contact finger 99 of the limit switch is. connectedto the coil 67 of the feed switch as, in the system shown in Fig.1.Thetwocontact-fingers 98 and 100 are connected to the contact fingers 91and 89 of the pilot switch through the reversing switch 121 as in thesystem shown in Fig. 1. I When thepilot switch is operated at the end ofthe cutting stroke, a circuit is completed throughthe. contact fingers98 and 99 and the contactsegments 94 and 97 for operat-' ing' the, feedswitch 27. The feed switch serves, ashereto'fore'set forth, to completea circuit throughthe feed motor. V The seg ment 91min the drum 96, asshown in Fig. 3 of the drawings, serves cuit or the feed motor closeduntil such motor has rotated the shaft ,9 andjthe gear wheel, 10,.through 180 degrees.

sumed that the manually operated switch 132 has previously been closedin order to obtain double feeding movements by. the feed motor..The'circuit for the coil 67 of tho ,switch27 is'thenconipleted throughthe switch 130 and the switch 132 after the contact finger 98 isseparated from the contact segment 94. The switch 130 is maintainedclosed by the cam member 128 until the shaft 9 has made a completerotation. During such movemeng'it isiapparentthe gear wheel 10 is firstreturned to initial positionand then effects a second'fecding movementof degrecs. Thus, double feed ing movementby the motor is effected. i phen thejlimit switch is'operated at the end of the return stroke, thecircuit for the coil 67 of the feed switch closed through the contactfingers 99 and 100 which are bridged bythe contact se ments 95 and 97The contact segment 95, w ich extends'haif similar to that shown in I tomaintain the cirlllfl lit) way round the drum ()6, maintains the circuitof the feed motor closed until the gear wheel 10 has made a rotation of180 degrees. Thus the feed mechanism is returned to initial position.The cam member 128 is definitely set with regard to the limit switch andserves to close the switch 130 for one complete rotation of the limitswitch.

Modifications in the system, and in the arrangement and location ofparts may be made within the spirit and scope of my invention and suchmodifications are intended to be covered by the appended claims.

hat I claim is:

1. In a control system for a machine tool,

the combination with a feed motor for effecting feeding movements of thecutting tool on the machine, and a pilot switch for closing the motorcircuit in accordance with the operation of the machine, of a limitswitch rotated by the feed motor for opening the feed motor circuitafter a predetermined feeding movement by the motor, and auxiliary meanscomprising a switch for chang ing the length of the feeding movementeffected by the motor.

2. In a'control system for a machine tool, the combination with areciprocating member, a feed motor for effecting feeding movements ofthe cutting tool on the machine, and a pilot switch for closing the feedmo tor circuit at each end of the stroke of the reciprocating member, ofa limit switch operated by the feed motor for opening the feed motorcircuit after a predetermined feedingmovement, a second limit switchoperated by said feed motor and adapted to change the length of thefeeding movements, and means for selectively connecting the feed motorto be controlled by one of said limit switches.

In a control system for a machine tool, the combination with areciprocating member, a feed motor for effecting feeding movements ofthe cutting tool on the machine, and a pilot switch for closing thecircuit of the feed motor in accordance with the op eration of thereciprocating member, of two limit switches operated by the feed motorfor limiting the feeding movements to different amounts, and a switchfor connecting the feed motor to be operated by either one of said limitswitches.

4. In a control system for a machine tool, the combination with areciprocating member, a feed motor for effecting feeding movements ofthe cutting tool on the machine, and a pilot switch for'closing thecircuit of the t'ee'd motor in accordance with the operation of thereciprocating member. of two limit switches mechanically connected tosaid motor for rotation at *diflerent speeds and adapted to effectdifferent lengths of feeding movements by the motor, and a limitthefeeding movements of switch for selectively connecting the motor to saidlimit switches.

In a control system for a machine tool, the combination with a feedmotor, and a pilot switch for operating the feed motor, of a limitswitch operated by the feed motor for limiting the feeding movements, asecond limit switch operated by said motor for changing the limit of thefeeding movements, and electrical means for selectively connecting thefeed motor to one of said limit switches.

6. In a control system for a machine tool, the combination with a feedmotor, and a pilot switch for operating the feed motor, of two limitswitches operated at ditt'erent speeds by the feed motor and serving tosaid motor, and means comprising a switch for connecting one or theother of said limit switches to the feed moto' according to the lengthof feeding movements desired.

7. In a control system for a machine tool, the combination with a feedmotor, and a pilot switch for operating the feed motor in accordancewith the operation of the machine tool, of a shaft operated by the feedmotor, a limit switch mounted on said shaft and adapted to limit thefeeding movements, a second limit switch geared to said first limitswitch, said gearing serving to operate the second limit switch at adifferent speed from the first limitswitch to change the length of thefeeding movements, and means comprising a switch for selectivelyconnecting the motorto one of the limit switches.

8. In a control system for a machine tool, the combination with a feedmotor, and a pilot switch for operating the feed motor in accordancewith the operation of the machine tool, of a limit switch mechanicallyconnected to the feed motor to be rotated thereby, a second limit switchmechanically connected to the first limit switch to be rotated at adifferent speed, and means for selectively connecting the motorelectrically to the limit switches.

9. In a control system for a machine tool, the combination with areciprocating member, a fecdmotor for etl'ecting feeding movements ofthe. cutting tool on the machine, and a pilot switch for operating thefeed motor in accordance with the movement of the reciprocating member,of a shaft operated by the feed motor, a limit switch mounted on saidshaft andadapted to limit'the feeding movements, a second limit switchgeared to said first limit switcli,-said gearing serving to operate thesecond limit switch at a different speed from the first limit switch tochange the length of the feeding movements, and means comprising aswitch for selectively connecting the motor to one of said limitswitches.

10. In a control system for a machine of two limit switches operated bythe feed 10 tool, the combination with a reciprocating motor forlimiting the feeding movements member,-a main motor for operating thereto different amounts and a switch for conciprocating member, a feedmotor for efi'eetnecting the feed motor to be operated by ing feedingmovements of the cutting tool on either one of the stud switches. themachine, and a pilot switch for control- In testimony whereof, I heretoai'iix my 15 ling the main motor and for closing the cirsignature. cuitof the feed motor in accordance with the operation of the reciprocatingmember, HAROLD L. BLOOD.

